The incidence of age-related diseases continues to rise as the number of Americans over the age of 65 grows. As a result, research is now focused on discovering methods to promote longevity. Although few molecular indicators of biological age have been indentified, we and others have recently shown that p16INK4a serves a robust and accurate marker of mammalian aging. Induction of p16INK4a correlates directly with chronological age in rodents and can be slowed by anti-aging strategies such as caloric restriction. In addition, our preliminary data show that p16INK4a levels are decreased by moderate exercise in healthy human subjects. Despite these data, the mechanisms by which lifestyle modification promotes longevity remain largely undefined. Herein, I will exploit the unique properties of p16INK4a as an aging biomarker to assess the tissue- specificity of anti-aging strategies. To do this, I have developed a novel knockin reporter allele, p16-LUC, which expresses firefly luciferase under control of the endogenous p16INK4a promoter. Importantly, my preliminary data show that induction of this allele correlates with cellular senescence in vitro and can be visualized in living animals. Using these mice I plan to address the following specific aims: 1) Characterize the p16- LUC allele under conditions relevant to the mammalian aging process, 2) Investigate the influence of diet and exercise on the induction of p16INK4a, 3) Determine the time- dependent and organ-specific effects of diet and exercise on p16INK4a promoter occupancy. PUBLIC HEALTH RELEVANCE: These studies will determine the potential of a new mouse model to predict how exercise and diet influence biological aging. In addition, we will gain insight into the processes that cause our bodies to age, helping us to develop new strategies that promote human health and longevity.